Home AR-15 Trouble Shooting: AR-15 Pistol Short Stroking

Trouble Shooting: AR-15 Pistol Short Stroking

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I recently took my AR-15 5.56 Pistol to the range. It was short stroking. Here is the problem and how I addressed it to find a solution…

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50 COMMENTS

  1. After you claimed the gunsmith was an expert, it makes me want to check the gas system LOL. Gas port size, gas block to gas port alignment, barrel to block journal size, gas tube, gas tube button gauged, gas key opening spec, reverse torque test, 3 bore sizes in bolt carrier, bolt tail and shoulder support size all need to be specked. Then you have to see if the gas port was sized for weak or NATO spec ammunition. Why people think a heavier buffer will fix a short stroking malfunction is nuts, it will make it worse. One other thing, get rid of your captive trigger- hammer pins. They are designed to rotate. Most 5.56 chambered rifles are not true 5.56 chambers, you need a 1.4646 head space gauge, not a 223 1.4636 gauge most sell as a NATO go gauge. Then you need to check the throat since most do not have a 5.56 throat. A function gauge will check both these at one time..Another test is the buffer spring compression stack test and the full recoil gas key- receiver full compression tolerance spec test…

  8. Buffer spring! I have an 10.5” PSA AR15 A new lower i built short stroked with my upper. the buffer spring was too long it measured 11 1/4 thats the max length 10 1/4 is the min
    The spring in my 10.5 Measured 10 3/8 it works fine.
    The 11 1/4 short stroked i got a 10 1/2 spring that fixed the problem!!!!

  10. Same problem w my pistol 300 blkout shooting unsupressed subs. Changing to Nemo buffer spring helped a little. Multiple rounds will cycle before " click " however, still not completely solved. Gonna try different gas block

  12. I have built a 18 barreled piston driven Ar-15, and I'm having the same problem, it is failing to fed and failing to eject rounds, I have standard spring and 5 oz buffer. Going to try a lighter spring. and carbine buffer.

  15. I had a similar problem with my 10.5” ar build. The fix is simple, but first go through and make sure you have no leaks at the gas block, check the bolt carrier (take it apart and check the piston rings are offset to minimize leak by) and put in a standard buffer (the one with three weights in it). Once that’s all good, here is your answer..fill your mag with 5.56!! It has a higher pressure than a 223, like 3-7,000 psi higher. That will cycle your bolt to the back properly, enjoy 😊

  24. Any follow-up on this? Did the buffer Spring fix it? Even though your high speed friend put the gas system on, that doesn't mean the parts themselves can't be defective. I have a 7.5 inch barrel on my 300 Blackout. I'm having the same problem but I bought a pistol length buffer tube/buffer/spring set. I'm also using a pigtail gas tube that wraps around the barrel three times before going into the gas key, and I have a suppressor attached. The weapon ejects the shell every time but fails to load the next round. I'm suspicious that the gas tube may not have a great seal where it goes into the gas block. I used the spaghetti noodle trick to line up the gas block on the barrel so I know that isn't the problem. I also removed the suppressor and fired a couple of rounds with no change. It would help a great deal if you would follow-up in the comments as to whether the buffer spring worked. Thanks.

  27. Dude, you've helped me a great deal. Your three or 4 videos helped me to address the same issue I am having with my Zev Tech 300 BO. It's an 8.5 inch. I plan on changing the buffer tube and spring and go from there. Not allot of videos out there on short stroke and fixes for pistols. Thanks man!

  28. You can’t assume just because a knowledgeable person installed the gas block that it’s not the culprit. Minor manufacturing defects in the gas block that bleed off gas are often not visible until you test fire a weapon. Look for fouling around the gas block to see if there is any bleed off before you rule that out.

  31. Oh yeah quick buffer spring fix leave your charging handle back over night it needs to compress cause it's too much tension from the spring. Me and my friend did this compared it to the same size one that was just out the box and it worked flawlessly

  33. Stupid question but I've had customers bring me the same problem and they are forgetting the #1 rule of ar15s you can't run them dry they will short stroke

  34. Did you even have the butt stock against your shoulder when you were shooting? I couldn't tell…. If you didn't, it's kinda like limp wristing a pistol. If you had been shouldering the gun, then you would have probably needed that heavy buffer, and spring. Pretty simple physics, bro.

  37. I built a 300 Blackout AR Pistol with a 7.5 inch barrel …. out of spare parts and only ordered a barrel and a flash hider and the rest was with spare parts. The gas tube is a “pig tail” that gave it probably a medium length as a gas tube curled around the barrel. We it would fire one round only and most of the time eject the used cartridge and from time to time the bolt carrier would catch the used cartridge on its way out and never cycle a new round … mags are Magpul mags made for the 300 Blackout …. thinking from what you showed a different weight buffer and spring … any suggestions?

  39. You might rely more on common sense than on the forums. If it's short stroking and also failing to feed it's because there's too much resistance, assuming your gas system checks out okay. You need to reduce that resistance by going to a lighter buffer and or buffer spring, which is what you apparently did to solve the problem. Short stroking is evidence of the system being under gassed so instead of using an H3 buffer you do the opposite and substitute a standard carbine buffer to decrease the resistance and make it easier for the bolt to come all the way back.

  41. Polishing chamber and feed helps. Switching bolts identified which bolt is effective 7075 is lighter than 9310 steel. Could try a competition bolt… last buffer spring heavy to light….Trying these various setups drastically improves performance past the break in period. …. To reliability. ..

  45. Really liked your video, have a question for you. I have a PSA 10.5 AR pistol in 5.56, took it out and had several jams and double feeds. The neck of the cases had small indentations them that jammed. I installed a Fulton Armory Binary trigger along with the heavy duty spring that came with the trigger. Gun will not cycle reliably so I ordered a flat wire spring, I also have spring that is much shorter that I haven't tried. I am using a standard carbine buffer, do you have any suggestion?

  47. This happens to me whenever i use ammo that isn't federal .223…I can't stand it cause i have other ammo and i want it to work for all types of ammo. My guess is im undergassed….

  48. I had a rifle short stroking………turns out my anti- rattle(accu wedge) was sticking up just enough to rub the bolt ,and slow it down. I cut off an eight inch off it ,re-assembled,and she ran like a sewing machine .

  49. I built a 10.5" pistol for a truck gun and right off the bat I noticed it was ejecting the spent casings at roughly 4o'clock. So I swapped out the BCG for a lighter semi auto and cut a few coils off the buffer spring and its ejecting 90 degrees from the muzzle now, right at 3o'clock. Ever since then I haven't had a single short stroke or failure to lock open on an empty mag. Little tip though, if you do end up cutting the spring, take it slow and only cut off 1 or 2 coils at a time and test fire in between so you don't end up cutting too much.

  50. I didn't read all the comments but it sounds like you need an adjustable gas block or adjustable gas key. This will allow you to fine tune your AR Pistol. You can use a Carbine Buffer once you change these parts. You only need to change one or the other not both. Take a look at a few Youtube videos on these subjects.

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